1. Field of the Invention
The present invention relates to an environmentally-friendly vehicle sound generator apparatus and a control method thereof. More specifically, the present invention relates to an environmentally-friendly vehicle sound generator apparatus and a control method thereof, which senses various operation states of a vehicle and plays back various kinds of operating sounds according to the sensed vehicle operation states or in different playback methods so that a virtual sound, i.e., an operating sound, which is close to a real engine sound according to the vehicle operation states, can be generated and output to be delivered to a driver or a pedestrian, thereby further securing safety of the pedestrian, and inducing a safe drive of the driver.
2. Description of Related Art
In recent years, due to depletion of energy, the development of an environmentally-friendly vehicle as an alternative transportation means is in increasingly active progress. Examples of representative environmentally-friendly vehicles include hybrid vehicles, electric vehicles, hydrogen fuel cell electric vehicles and the like. Since such an environmentally-friendly vehicle does not adopt a method of operating an engine, it does not generate an engine noise or the like while driving unlike an existing internal combustion engine vehicle. Accordingly, the establishment of regulations on the environmentally-friendly vehicles is being prepared to protect pedestrians around a vehicle, and the research and development of a virtually operating sound generation system of an environmentally-friendly vehicle are required in relation to the establishment of regulations.
That is, an environmentally-friendly vehicle such as a hybrid vehicle, an electric vehicle, a hydrogen fuel cell electric vehicle or the like does not generate an engine's unique sound generated from a gasoline vehicle or a diesel vehicle. For this reason, there occur problems in that an accident may occur since a pedestrian does not recognize a vehicle approaching the pedestrian or a vehicle at a place such as an alley or an indoor parking lot, and in that it is also difficult for a driver to recognize the startup state or the current state of a vehicle since a vehicle noise is not generated.
Furthermore, a vehicle including a recharge energy system, such as an electric vehicle, a hydrogen fuel cell electric vehicle or the like, entails problems in that it is difficult to know whether the recharge is started or finished, and in that it is very inconvenient to use the vehicle due to extreme insufficiency of vehicle information that can be recognized by a driver in relation to a risk caused by discharge of a battery or deficiency of fuel.
In an attempt to solve such problems, apparatuses for generating a virtual engine sound for environmentally-friendly vehicles are recently developed. However, virtual engine sound generation apparatuses that are being currently developed simply generate a sound similar to an engine sound associated with the driving of a vehicle and cannot provide various functions to a pedestrian or a driver, and its technical level is still insignificant since information on the current state of the vehicle is provided insufficiently.
In Particular, a conventional apparatus for outputting a sound similar to an engine sound performs a fade-out function of decreasing an output sound when the vehicle travels at a predetermined speed or higher. The fade-out function employs a method of unconditionally blocking the output of the sound simply in proportion to the speed of the vehicle or when a predetermined time period is elapsed after the vehicle speed exceeds the predetermined speed (see FIG. 1). In addition, such a method involves a problem in that since a virtual warning sound is frequently turned on and off in a traffic jam state in which traveling and stopping of the vehicle is repeated due to a frequent change in speed, i.e., a road traffic congestion, around the speed range of the fade-out function, a pedestrian, a driver or a passenger may suffer from a feeling of displeasure or uneasiness in the traffic jam state.
As an example of the prior art, there has been disclosed Korean Patent Registration No. 10-985767.